FRACTURE-MECHANICS OF PLATES AND SHELLS APPLIED TO FAIL-SAFE ANALYSISOF FUSELAGE .1. THEORY

In this paper, a general theory on the asymptotic field near the crack tip for plates and shells with and without shear deformation effect i s established. It is found that four stress intensity factors, two for symmetrical and antisymmetrical stretching and two for symmetrical an d antisymmetrical bending, are required to describe arbitrary asymptot ic fields near the crack tip for plates without shear deformation. An additional stress intensity factor is required for the transverse shea ring force induced by antisymmetrical bending when the shear deformati on is included in the analysis. It is also proven by means of the comp lex variable technique that for problems of plates with shear deformat ion, there exist similarities in the asymptotic expressions of moments and membrane forces and also in the asymptotic expressions of in-plan e displacements and rotations of the mid-surface. The energy release r ate associated with crack growth in the direction of the crack line ca n be expressed in terms of stress intensity factors by means of Irwin' s method of work and energy associated with a virtual crack extension. A combined stress intensity factor can be defined through the total e nergy release rate. The theory of the fracture of plates is generalize d and applied to the study of problems in the fracture of shells. An e xample of an infinitely long cylindrical shell with a circumferential crack subjected to remote axial tension is given to demonstrate the ap plication of the theory and to test the accuracy of the numerical anal ysis used for the problem. (C) 1997 Elsevier Science B.V.